1. Field of the Invention
The present invention relates to an illumination device and a display device.
2. Description of the Related Art
A liquid crystal display device broadly consists of a liquid crystal panel for displaying images and a backlight device as an external light source. In particular, a backlight device that is disposed at the rear side of a liquid crystal panel is referred to as a “direct type”.
A device described in Japanese Patent Laid-Open No. 2001-22285 is known as one example of this kind of direct type backlight device. As shown in FIG. 13A and FIG. 13B, this backlight device 1 consists of a base 2 that has a box shape in which the top surface side is open, a plurality of fluorescent tubes 3 that are mounted inside the base 2, and a plurality of optical sheets 4 that are disposed in a state in which they are superimposed in the open portion of the base 2. Each of the fluorescent tubes 3 are supported with respect to the base 2 in a posture in which the axis of each tube is parallel to each other and also to the surface along the direction of alignment. Light that is emitted from each of the fluorescent tubes 3 is supplied to the liquid crystal panel through the optical sheets 4.
The fluorescent tubes 3 as the light source of the backlight device 1 are one kind of linear light source. The distribution of light intensity of these light sources is as follows. More specifically, as shown in FIG. 14, when the linear light source (fluorescent tube 3) is viewed laterally in the axial direction thereof, the light intensity is strongest in a direction that is perpendicular to the axial direction and the light intensity gradually weakens as the viewing direction nears the axial direction from the perpendicular direction.
Accordingly, when the fluorescent tubes 3 are disposed in the manner shown in FIG. 13A and FIG. 13B, there is a problem that although the backlight device 1 appears sufficiently bright when viewed from the front surface in the illumination direction, the backlight device 1 appears relatively dark when viewed from a diagonal direction.